The Valve Wizard
Adam's Amplifiers A neat amateur site with an excellent overview of tone stacks used in guitar amps.
AikenAmps American amp maker with some great technical info and circuit tutorials.
www.ax84.com American site dedicated to DIY guitar amps. Projects and info, plus what is probably the best open forum on the internet dedicated to this subject.
DIY Fever A Serbian enthusiast with many amp and pedal related projects, and some cool software too!
www.duncanamps.com American site with many useful
resouces and schematics, particularly the 'Tone Stack Calculator'; a free program allowing you to model common types of tone circuit.
Effectrode; wonderful valve-based effects pedals, based in Staffordshire!
http://ken-gilbert.com Ken Gilbert's site contains some interesting articles on circuit theory.
Nixie World Absolutely loads and loads of books and data on nixie tubes and counting tubes.
www.projetg5.com A French valve guitar amp DIY site, also with an excellent forum.
frank.pocnet.net An excellent and very extensive collection of valve datasheets.
http://studentweb.eku.edu A site dedicated to the Fender HotRod Deluxe, with some useful introductory info on valve amps.
www.tubecad.com Web journal of advanced valve circuit analysis and experiments, for hifi.
www.tube-classics.de Detailed archive of the various iterations of vintage audio valves.
www.thermionic.info An excellent collection of old valve-related books and magazine articles available for free download.
18watt.com Site devoted to the Marshall 18Watt amplifier, with project variations, resources and an excellent forum.
UK and European parts suppliers:
6v6.co.uk UK site specialsing in new parts for valve radios. Limited and variable range but reasonably priced.
airlinktransformers.com Very affordable toroidal transformers including 240V:240V isolating transformers. Based in Essex.
AstonElectronics.co.uk Staffordshire supplier of amp parts and kits, and the manufacturer of "Volt" amplifiers.
askjanfirst.com German site, mainly selling parts for amplifier and radio repair (transformers especially). Variable prices, although the transformer shields are truly excellent and difficult to obtain anywhere else. Cheap postage and reliable delivery.
ampmaker.com An enthusiast in the south of England selling kits and all the basic hardware for amp building, including some hard to find items. Good prices and an excellent and friendly service.
banzaieffects.com German site selling hardware and components for effects pedals, with some amp parts, components and valves aswell. Transformers are overpriced, but most other items are extremely cheap. Useful products include valves, sockets and shields, knobs, cabinet feet, corners and handles, as well as direct replacement parts for Fender, Marshall, Vox and other well known amps. Cheap postage and very reliable delivery.
BitsBox.co.uk An amazingly cheap supplier of general electronic components for hobbyists, based in Solihull.
BlueBellAudio.com Wide range of reasonably-priced amp parts, including Hammond transformers.
cpc.co.uk Uk electronics wholesaler (part of Farnell) selling a truly massive range of components, tools and hardware including guitar speakers/drivers (but no valves). Excellent prices and free delivery on orders over £40.
dagnall.co.uk An old favourite transformer manufacturer. Apparently they will now make valve transformers to order too!
diyAudioComponents.com High quality ribbon microphones and related parts, based in Latvia.
DoctorTweek.co.uk Outstanding low-cost hobby site for pedal building parts, and also carries a wonderful selection of control knobs.
edicron.co.uk Main UK wholesaler of all current production valves. Catering for the private individual as well as businesses, they even provide a valve branding service. Catalogue available on email request, prices unbeatable.
www.ElectroJumble.Org Nottingham seller of general amp and guitar hardware, including an excellent selection of reasonably priced new valves.
www.HotRoxUK.com Seller of various vintage electronics parts and literature, in the New Forest area.
http://livinginthepast-audioweb.co.uk/valveaudio.html Distributor of valve transformers made by Danbury Electronics (who make transformers for Ampmaker.co.uk). Very attractive transformers , though prices have recently gone up.
maplin.co.uk High-street electronics retailer. With an outlet in most larger towns, Maplins is easily acessible if a little understocked. Prices are generally extortionate, though they do sell a good 25W output transformer online.
ModulusAmplification.com/ Excellent supplier of amp parts, based in Scotland.
PrimaryWindings.com/ UK manufacturer of reasonably priced valve transformers.
rapidonline.com Electronics wholesaler in England selling a huge range of components, tools and hardware, as well as a selection of valves and sockets. Other useful products are Q-max metal hole-punches and solid core hook-up wire. Free catalogue and free delivery on orders over £25 within the UK. Among the cheapest prices for parts available anywhere.
http://rswww.com The well known Radio Spares electronics wholesaler. Vast range of products. Prices are generally too high for the individual, prefering to cater for large bulk orders. Most useful products are their vintage-style turrets and unusual retro knobs.
ShedPickups.com Welsh manufacturer of handwound guitar pickups and reasonable prices.
SwitchElectronics.co.uk Supplier of general electronic components similar to Rapid, based in Hull.
Trans-Tronic.co.uk Supplier of drop-in and custom transformers, based in Chesterfield.
Tube-Store.com World-wide supplier of valves at excellent prices.
tube-and-valve-electronics.co.uk Billington Export- seller of valves and other components.
ValvePowers.co.uk London based seller of valve amp kits and parts, including a very reasonably priced 18W output transformer.
verelec.com An excellent site in the Netherlands, selling a good range of valve amp related components.
vvtTransformers.com A wide range of power and output transformers. Update 2016: It looks like they may have ceased trading.
watfordvalves.com London based retailer of valves. Comprehensive range of new and used tested valves.
The load line plotter: A simple spreadsheet program I have written; it calculates gain and output impedances, and plots anode/cathode load lines and frequency reponse for some common triodes. Click here to download the Excel version (837kB) Also thanks to Eric Seibt for the Open Office version (800kB)
The Optimised SRPP Amp: An article from AudioXpress on the SRPP as an OTL amplifier. Click here to download the PDF (257kB)
The determination of Quiescent Voltages and Currents in Pentode Amplifiers (Shimmins) An article from Electronic Engineering, September 1950. Click here to download the PDF (580kB)
Triodes at Low Voltages: An article I have written on the design of triode circuits under starved conditions. Click here to download the PDF (190kB)
Twin Triode Phase-Splitting Amplifier (Clare): An article from Electronic Engineering, February 1947, on what eventually became the preamp for the Mullard 5-10 and 5-20, among many other iconic hifi amplifiers. Click here to download the PDF (560kB)
Self-Split, Push-Pull Circuit Analysis (Amose): An article from Wireless Engineer, February 1946. Click here to download the PDF (800kB)